Poly (arylene thioether) block copolymer fibers and production process thereof

ABSTRACT

Disclosed herein are poly(arylene thioether) block copolymer fibers formed by melt-spinning a thermoplastic material composed of (A) 100 parts by weight of a particular poly(arylene thioether) block copolymer, (B) up to 50 parts by weight of at least one other thermoplastic resin and (C) up to 10 parts by weight of at least one filler. The poly(arylene thioether) block copolymer alternatively comprises at least one poly(arylene thioether-ketone) block having predominant recurring units of the formula ##STR1## wherein the --CO-- and --S-- are in the para position to each other and at least one poly(arylene thioether) block having predominant recurring units of the formula

This application is a division of application Ser. No. 07/424,638 filedOct. 20, 1989, now allowed.

FIELD OF THE INVENTION

This invention relates to fibers using a novel poly(arylene thioether)block copolymer comprising poly(arylene thioether-ketone) blocks andpoly(arylene thioether) blocks, and more specifically to fibers whichare formed solely from the block copolymer having high melt stabilitysufficient to permit application of conventional melt processingtechniques or a thermoplastic material composed of the block copolymerand at least one other thermoplastic resin and/or at least one fillerand have high heat resistance, especially, excellent durability atelevated temperatures, in other words, excellent retention of mechanicalstrength and the like when held at an elevated temperature for a longperiod of time; and to a production process thereof.

This invention is also concerned with fibers using a block copolymercontaining a specific stabilizer and having still improved meltstability.

BACKGROUND OF THE INVENTION

In the fields of the electronic and electrical industry and theautomobile, aircraft and space industries, there is a strong demand inrecent years for crystalline thermoplastic resins having high heatresistance of about 300° C. or higher in terms of melting point andmoreover easy melt processability.

Recently, poly(arylene thioether-ketones) (hereinafter abbreviated as"PTKs") have drawn attention for their high melting points. Variousstudies are now under way thereon.

There are some disclosure on PTKs, for example, in Japanese PatentLaid-Open No. 58435/1985, German Offenlegungsschrift 34 05 523 Al,Japanese Patent Laid-Open No. 104126/1985, Japanese Patent Laid-Open No.13347/1972, Indian J. Chem., 21A, 501-502 (May, 1982), Japanese PatentLaid-Open No. 221229/1986, U.S. patent specification No. 4,716,212, U.S.patent specification No. 4,690,972, European Patent Publication No.0,270,955 A2, European Patent Publication No. 0,274,754 A2, EuropeanPatent Publication No. 0,280,325 A2, etc.

Regarding the PTKs described in the above publications, neither moldingnor forming has however succeeded to date in accordance withconventional melt processing techniques. Incidentally, the term"conventional melt processing techniques" as used herein means usualmelt processing techniques for thermoplastic resins, such as extrusion,injection molding and melt spinning.

The unsuccessful molding or forming of PTKs by conventional meltprocessing techniques is believed to be attributed to the poor meltstability of the prior art PTKs, which tended to lose theircrystallinity or to undergo crosslinking and/or carbonization, resultingin a rapid increase in melt viscosity, upon their melt processing.

The present inventors thus conducted an investigation with a view towarddeveloping a process for economically producing PTKs having meltstability sufficient to permit the application of conventional meltprocessing techniques. The investigation led to the successful provisionof PTKs having significantly improved heat stability upon melting(hereinafter called "melt stability") (Japanese Patent Laid-Open No.54031/1989).

It has also found that the melt stability of the melt-stable PTKs uponmelt processing can be improved further by the addition of a basiccompound such as the hydroxide or oxide of a Group IA or Group IIA metalof the periodic table to them (Japanese Patent Application No.142772/1988).

The melt-stable PTKs obtained as described above have a high meltingpoint, typified by the extremely high melting point of the homopolymerwhich reaches as high as about 360° C. This is however not all good.Their melt processing temperatures are high accordingly, so that meltprocessing facilities for high-temperature processing are required.Further, a stringent temperature control is required to perform meltprocessing without deterioration by heat.

The melt-stable PTKS are generally obtained as fine powders having aparticle size of approximately 5-20 μm. This has led to an additionalproblem upon their production such that they show poor handlingproperties in their collection step after polymerization, especially infiltration, washing, drying and transportation. Still further problemshave also arisen such as poor metering property upon melt processing andoccurrence of blocking in hoppers or the like.

OBJECTS AND SUMMARY OF THE INVENTION

An object of this invention is to provide fibers which have high heatresistance, especially, excellent durability at elevated temperatures,in other words, excellent retention of mechanical strength and the likewhen held at an elevated temperature for a long period of time.

Another object of this invention is to obtain a polymer with improvedprocessability and handling properties while retaining the excellentproperties, such as heat resistance and crystallinity, of theaforementioned melt-stable PTKs as much as possible and then to providefibers having the above-described properties by using the above polymer.

The present inventors then attempted to produce a PTK-PATE blockcopolymer in which a poly(arylene thioether) (hereinafter abbreviated as"PATE") having recurring units of the formula ##STR2## is incorporatedas blocks in the chain of a melt-stable PTK. As a result, it has beenfound that a poly(arylene thioether) block copolymer having excellentprocessability and high crystallinity can be obtained by using as aprepolymer a PATE, which has a particular average polymerization degreeand contains terminal thiolate groups and/or thiol groups as reactiveterminal groups, and reacting the PATE prepolymer with a4,4'-dihalobenzophenone and an alkali metal sulfide under specificconditions in an organic amide solvent.

It has also been found that a block copolymer having excellentproperties can be obtained by reacting a PATE prepolymer with a PTKprepolymer under specific conditions.

It has also been uncovered that each of these block copolymers can beobtained as granules having good handling properties from itspolymerization systems by a conventional collection method.

It has also been revealed that the block copolymers have high meltstability upon melting and formed or molded products such as fibers canhence be obtained easily by a conventional melt processing techniquefrom the block copolymers alone or a thermoplastic material which is acomposition of the block copolymers, at least one other thermoplasticresin and/or at least one filler.

In addition, it has also been found that thermoplastic materialsimproved still further in melt stability and crystallinity reduction andimproved in problems such as sticking of thermal decomposition productsto resin residence areas of melt processing equipment can each beobtained by adding a specific basic compound, optionally along with ananti-oxidant, to the above-described thermoplastic material containingthe block polymers.

The present invention has been brought to completion on the basis ofthese findings.

In one aspect of this invention, there is thus provided poly(arylenethioether) block copolymer fibers formed by melt-spinning of athermoplastic material comprising:

(A) 100 parts by weight of a poly(arylene thioether) block copolymer(Component A) alternately comprising (X) at least one poly(arylenethioetherketone) block having predominant recurring units of the formula##STR3## wherein the --CO-- and --S-- are in the para position to eachother and (Y) at least one poly(arylene thioether) block havingpredominant recurring units of the formula ##STR4##

(a) the ratio of the total amount of the poly(arylene thioether) block(Y) to the total amount of the poly(arylene thioether-ketone) block (X)ranging from 0.05 to 5 by weight,

(b) the average polymerization degree of the poly(arylene thioether)block (Y) being at least 10, and

(c) said block copolymer having a melt viscosity of 50-100,000 poises asmeasured at 350° C. and a shear rate of 1,200/sec;

(B) optionally, up to 50 parts by weight of at least one otherthermoplastic resin (Component B); and

(C) optionally, up to 10 parts by weight of at least one filler(Component C).

In a further aspect of this invention, there is also provided a processfor the production of poly(arylene thioether) block copolymer fibersfrom a thermoplastic material composed of:

(A) 100 parts by weight of poly(arylene thioether) block copolymer(Component A) alternately comprising (X) at least one poly(arylenethioetherketone) block having predominant recurring units of the formula##STR5## wherein the --CO-- and --S-- are in the para position to eachother and (Y) at least one poly(arylene thioether) block havingpredominant recurring units of the formula ##STR6##

(a) the ratio of the total amount of the poly(arylene thioether) block(Y) to the total amount of the poly(arylene thioether-ketone) block (X)ranging from 0.05 to 5 by weight,

(b) the average polymerization degree of the poly(arylene thioether)block (Y) being at least 10, and

(c) said block copolymer having a melt viscosity of 50-100,000 poises asmeasured at 350° C. and a shear rate of 1,200/sec;

(B) optionally, up to 50 parts by weight of at least one otherthermoplastic resin (Component B); and

(C) optionally, up to 10 parts by weight of at least one filler(Component C), which comprises melt-extruding the thermoplastic materialat 300-400° C. through a spinneret, stretching the resultant filamentsat 90°-190° C. and a draw ratio of 1.2-8 times, and then heat-settingthe thus-stretched filaments at 100°-340° C. for 0.1-1000 seconds.

In the fibers of the present invention and the production processthereof, the thermoplastic material may further comprises, per 100 partsby weight of the poly(arylene thioether) block copolymer (Component A),0.1-10 parts by weight of at least one basic compound (Component D)selected from the group consisting of hydroxides, oxides and aromaticcarboxylates of group IIA metals of the periodic table other thanmagnesium, and aromatic carboxylates, carbonates, hydroxides,phosphates, including condensation products, and borates, includingcondensation products, of group IA metals of the periodic table and 0-10parts by weight of at least one antioxidant (Component E) selected fromthe group consisting of hindered phenolic compounds, phosphoruscompounds and hindered amine compounds. Use of this thermoplasticmaterial permits the provision of the fibers improved still further inmelt stability.

According to this invention, fibers having high heat resistance,especially, excellent durability at elevated temperatures, in otherwords, excellent retention of mechanical strength and the like when heldat an elevated temperature for a long period of time can easily beobtained by a conventional melt processing technique from athermoplastic material comprising a high-crystalline poly(arylenethioether) block copolymer, which has high melt stability sufficient topermit application of the conventional melt processing technique and hasgood processability and handling properties, or if desired, athermoplastic material which is a composition of the block copolymer, atleast one other thermoplastic resin and/or at least one filler.

This invention can also provide, from a thermoplastic material blendedwith a basic compound or the like, fibers having excellent physicalproperties while improving problems such as the melt viscosity increase,the crystallinity reduction and the sticking of thermal decompositionproducts to resin residence areas of melt processing equipment uponconventional melt processing.

The present invention will hereinafter be described in detail.

DETAILED DESCRIPTION OF THE INVENTION

[Component A]

(Poly(Arylene Thioether) Block Copolymers)

[Chemical structure of block copolymers]

The poly(arylene thioether) block copolymer useful in the practice ofthe present invention is a block copolymer alternately comprising (X) atleast one PTK block having predominant recurring units of the formula##STR7## wherein the --CO-- and --S-- are in the para position to eachother and (Y) at least one PATE block having predominant recurring unitsof the formula ##STR8##

The block copolymer of the present invention can have a desiredstructure containing both blocks in an alternate order, such as(X)-(Y)-(X)-(Y)-(X), m being 0 or an integer of 1 or greater or(X)-(Y)-(X)_(n) -(Y), n being 0 or an integer of 1 or greater.

It is however required that the weight ratio of the total amount ofblocks (Y) to the total amount of blocks (X) be within a range of0.05-5, preferably 0.1-4, more preferably 0.15-3.

The block (X) serves to impart high degrees of heat resistance andcrystallinity to the block copolymer. On the other hand, the block (Y)contributes to the reduction of the processing temperature and thegranulation while maintaining the high crystallinity. Therefore, anyweight ratios of the total amount of blocks (Y) to the total amount ofblocks (X) smaller than 0.05 are too small to achieve any sufficientreduction in processing temperature or the granulation. To the contrary,any ratios greater than 5 lead to a substantial reduction in heatresistance and disturb the balancing between heat resistance andprocessability. Ratios outside the above range are therefore notpreferred.

It is essential for the block (Y) to have an average polymerizationdegree of at least 10, preferably 20 or higher.

If the average polymerization degree of the block (Y) is smaller than10, the resulting block copolymer becomes similar to a random copolymerso that physical properties such as crystallinity, heat resistance andmelt stability are all reduced substantially. Such small averagepolymerization degrees are therefore not preferred. In addition, anyunduly small average polymerization degree of the block (Y) leads toanother problem that a block copolymer of high molecular weight canhardly be obtained.

The block (X) and block (Y) can contain one or more recurring unitsother than their predominant recurring units of the formulae ##STR9## toan extent that the objects of this invention are not impaired.

Exemplary recurring units other than the above recurring units mayinclude: ##STR10##

In general, these other recurring units can be introduced into the blockcopolymer by using the corresponding various dihalogenated aromaticcompounds as comonomers.

[Physical properties of the block copolymer]

Physical properties and other characteristics of the poly(arylenethioether) block copolymer useful in the practice of this invention willnext be described in detail from the viewpoint of processability, meltstability, crystallinity and the like.

(1) Processability:

The melting point of PTK homopolymer is about 360° C. The extent of areduction in the melting point due to copolymerization with anothermonomer of a different kind, ΔTm=[360° C.-Tm (melting point ofcopolymer)] is generally proportional to the extent of a reduction inthe melt processing temperature. Accordingly, ΔTm can be used as anindex indicative of processing temperature reducing effect, namely,processability improving effect.

ΔTm may preferably be 10°-80° C., more preferably 20°-70° C., mostpreferably 30°-60° C. If ΔTm is lower than 10° C., there is a potentialproblem that the processability improving effect may not be sufficient.If ΔTm is higher than 80° C., there is another potential problem thatthe block copolymer may lose the characteristics as a heat-resistantresin. ΔTm outside the above range is therefore not preferred.

(2) Crystallinity:

One of great features of the block copolymers according to thisinvention resides in that they have not only excellent processabilitybut also high crystallinity. Crystallinity imparts high heat resistanceto a copolymer. To have a block copolymer equipped with high heatresistance, it is essential that the block copolymer has sufficientcrystallinity.

In general, melt crystallization enthalpy ΔHmc is proportional to thedegree of crystallization when a molten polymer undergoescrystallization. On the other hand, melt crystallization temperature Tmcserves as an index of the readiness of crystallization. Therefore, themelt crystallization enthalpy ΔHmc (400° C). and melt crystallizationtemperature Tmc (400° C.) of a block copolymer according to thisinvention as measured when cooled at a rate of 10° C./min immediatelyafter being heated to 400° C. in an inert gas atmosphere by means of adifferential scanning calorimeter (hereinafter abbreviated as "DSC") canbe used as indices of the crystallinity of the block copolymer.

In addition, residual melt crystallization enthalphy, ΔHmc (400° C./10min) and melt crystallization temperature, Tmc (400° C./10 min)measurable upon determination of the residual crystallinity, both ofwhich will be described subsequently, can be used as an index of notonly melt stability but also crystallinity.

The block copolymers of this invention may have a melt crystallizationenthalpy, ΔHmc (400° C.) of at least 15 J/g, preferably at least 20 J/g,and more preferably at least 25 J/g. On the other hand, Tmc (400° C.)may desirably be at least 180° C., with at least 200° C. being morepreferred. Block copolymers having ΔHmc (400° C.) smaller than 15 J/g orTmc (400° C.) lower than 180° C. may have insufficient heat resistanceas heat resistant polymers and are hence not preferred.

(3) Melt stability:

The greatest feature of the block copolymers according to this inventionresides in that they have melt stability sufficient to permit theapplication of conventional melt processing techniques.

Polymers of poor melt stability tend to lose their crystallinity or toundergo crosslinking or carbonization, resulting in a rapid increase inmelt viscosity, upon melt processing.

It is hence possible to obtain an index of the melt processability of apolymer by investigating the residual crystallinity of the polymer afterholding it at an elevated temperature of its melt processing temperatureor higher for a predetermined period of time. The residual crystallinitycan be evaluated quantitatively by measuring the melt crystallizationenthalpy of the polymer by a DSC.

Specifically described, it is possible to use as indices of the meltstability of a block copolymer its residual melt crystallizationenthalphy, ΔHmc (400° C./10 min) and melt crystallization temperature,Tmc (400° C./10 min), which are determined at a cooling rate of 10°C./min after the block copolymer is held at 50° C. for 5 minutes in aninert gas atmosphere, heated to 400° C. at a rate of 75° C./min and thenheld for 10 minutes at 400° C. which is higher than the melt processingtemperature of the block copolymer.

In the case of a copolymer having poor melt stability, it undergoescrosslinking or the like under the above conditions, namely, when it isheld for 10 minutes at the high temperature of 400° C., whereby thecopolymer loses its crystallinity substantially.

The block copolymers of this invention are polymers having the physicalproperties that their residual melt crystallization enthalpies, ΔHmc(400° C./10 min) are at least 10 J/g, more preferably at least I5 J/g,most preferably at least 20 J/g and their melt crystallizationtemperatures, Tmc (400° C./10 min) are at least 170° C., more preferablyat least 180 C, most preferably at least 190° C.

A block copolymer, whose ΔHmc (400° C./10 min) is smaller than 10 J/g orwhose Tmc (400° C./10 min) is lower than 170° C., tends to lose itscrystallinity or to induce a melt viscosity increase upon meltprocessing, so that difficulties are encountered upon application ofconventional melt processing techniques.

Further, the ratio of melt crystallization enthalpy to residual meltcrystallization enthalpy, namely, ΔHmc (400° C.)/ΔHmc (400° C./10 min)can also be used as an index of melt stability. Deterioration by heatbecomes smaller as this ratio decreases. Therefore, it is preferablethat ΔHmc (400° C./10 min) is at least 10 J/g and the above ratio is 5or smaller, more preferably 3 or smaller.

(4) Melt viscosity:

In this invention, the melt viscosity .sub.η * of each copolymer is usedas an index of its molecular weight.

Specifically, a polymer sample is filled in a Capirograph manufacturedby Toyo Seiki Seisaku-Sho, Ltd. and equipped with a nozzle having aninner diameter of 1 mm and an L/D ratio of 10/1 and is preheated at 350°C. for 5 minutes. Its melt viscosity η* is measured at a shear rate of1,200/sec.

The block copolymers of the present invention have a melt viscosityη^(*) of 50-100,000 poises, preferably 100-50,000 poises, morepreferably 150-10,000 poises.

Those having a melt viscosity η^(*) lower than 50 poises have an undulysmall molecular weight so that their flowability is too high to conductmelt-spinning by conventional melt processing techniques. Even if fibersare obtained, their physical properties are considerably inferior. Suchlow melt viscosities are therefore not preferred. On the other hand,those having a melt viscosity η^(*) higher than 100,000 poises have anunduly large molecular weight so that their flowability is too low toapply conventional melt processing techniques. Such high meltviscosities are therefore not preferred either.

Production Process of Block Copolymers

Processes for the production of the block copolymers include:

(1) addition of a dihalogenated aromatic compound consisting principallyof a 4,4'-dihalobenzophenone and an alkali metal sulfide to PATE blocks(Y) prepared in advance, whereby they are reacted to form PTK blocks(X); and (2) chemical coupling of PTK blocks (X) and PATE blocks (Y),said blocks (X) and (Y) having been prepared separately.

A. Raw materials for block copolymers:

In the process for the production of a block copolymer of thisinvention, are primarily employed an alkali metal sulfide and adihalogenated aromatic compound as principal raw materials for thepolymer as well as an organic amide solvent and water, including waterof hydration, as reaction polymerization media.

(1) Alkali metal sulfide:

Illustrative examples of the alkali metal sulfide useful in the practiceof this invention include lithium sulfide, sodium sulfide, potassiumsulfide, rubidium sulfide, cesium sulfide and mixtures thereof.

These alkali metal sulfides may each be used as a hydrate or aqueousmixture or in an anhydrous form.

(2) Dihalogenated aromatic compound:

The dihalogenated aromatic compound employed in the present inventionfor the formation of the PTK block (X), including a PTK prepolymer,consists principally of one or more dihalobenzophenones, i.e.,4,4'-dichlorobenzophenone and/or 4,4'-dibromobenzophenone.

The dihalogenated aromatic compound used for the formation of the PATEblock (Y), including a PATE prepolymer, consists principally of adihalobenzene such as p-dichlorobenzene or m-dichlorobenzene.

As other copolymerizable dihalogenated aromatic compounds, may bementioned, for example, dihalobenzophenones other than the 4,4'-isomers,dihaloalkylbenzenes, dihalobiphenyls, dihalodiphenyl sulfones,dihalonaphthalenes, bis(halogenated phenyl)methanes, dihalopyridines,dihalothiophenes and dihalobenzonitriles, and mixtures thereof.

It is also permissible to introduce a partially crosslinked and/orbranched structure by causing a trihalogenated or higher polyhalogenatedcompound to exist in a reaction system in such a small amount that theprocessability and physical properties of the copolymer may not beimpaired to any substantial extent.

(3) Organic amide solvent:

As organic amide solvents useful for the present invention, may bementioned N-methylpyrrolidone, N-ethylpyrrolidone, hexamethylphosphorictriamide, tetramethylurea, dimethylimidazolidinone, dimethylacetamide, amixed solvent thereof, etc.

B. Polymerization process and reaction conditions:

To prepare the PATE prepolymer in this invention, any processconventionally known for the polymerization of PATE can be adopted.However, for the reaction in which the PTK is formed in the presence ofthe PATE prepolymer, for the preparation of the PTK prepolymer and forthe reaction in which the PTK prepolymer and PATE prepolymer arecombined together to form a block copolymer, it is necessary to conductthe reactions under special conditions, namely, by maintaining a highwater content in the reaction systems, controlling the monomercompositions suitably, regulating the polymerization temperaturesappropriately, and limiting reaction time at high temperatures. It iseffective for the production of block copolymers having more preferablephysical properties, for example, to choose a suitable material for thereactor and to apply stabilization treatment in a final stage of thereaction.

Unless these reaction conditions are suitably controlled, it isdifficult to provide crystalline block copolymers having melt stabilitysuitable for conventional melt processing.

<Preparation processes of prepolymers>

(1) PATE prepolymer:

The PATE prepolymer employed as a raw material for the block copolymerof this invention can be prepared by having an alkali metal sulfide anda dihalogenated aromatic compound, which consists principally of adihalobenzene, undergo a dehalogenation/sulfuration reaction in thepresence of water in an organic amide solvent under the followingconditions (a)-(c):

(a) The ratio of the water content to the amount of the charged organicamide solvent is within a range of 0.2-5 (mol/kg), preferably 0.5-4.5(mol/kg).

(b) The ratio of the amount of the charged dihalogenated aromaticcompound to the amount of the charged alkali metal sulfide is within arange of 0.8-1.05 (mol/mol), preferably 0.8-1.0 (mol/mol), morepreferably 0.85-0.95 (mol/mol).

(c) The reaction is conducted at a temperature within a range of200°-280° C., preferably 210°-250° C., and should be continued until theaverage polymerization degree of the resulting prepolymer reaches atleast 10, preferably 20 or greater.

When the ratio of the amount of the charged dihalogenated aromaticcompound to the amount of the charged alkali metal sulfide is set at0.95 or greater (mol/mol), notably, 1.0 or greater (mol/mol) as theabove condition (b), the reaction product may be treated further withthe alkali metal sulfide to prepare a PATE prepolymer containing morethiolate groups as reactive terminal groups. The PATE prepolymer maycontain some crosslinked structure and/or branched structure introducedtypically by allowing a trihalobenzene or higher polyhalobenzene topresent in a small amount in the polymerization reaction system.

The PATE prepolymer is supposed to be a polymer having an averagepolymerization degree of at least 10, preferably at least 20 in view ofthe physical properties required for the block copolymer to be obtained.

In this invention, the number average molecular weight of the PATE blockin the stage of the prepolymer is determined by applying the methodwhich relies upon the numbers of terminal thiol groups, thiolate groupsand terminal halogen atoms.

Incidentally, it is preferred from the standpoint of reactivity that theratio of terminal thiolates, including thiol groups if any, to terminalhalogen atoms in the PATE prepolymer chain is at least 0.3 (mol/mol),more preferably at least 0.5 (mol/mol). If this ratio is smaller than0.3, the reactivity at the terminals of the PATE prepolymer isinsufficient thereby to make it difficult to obtain a block copolymer.

In passing, among the recurring units of the formula ##STR11## theparaphenylene sulfide unit of the formula ##STR12## is preferred becauseit can afford block copolymers excellent especially from the viewpointof crystallinity, melt stability, heat resistance, mechanical propertiesand the like.

(2) PTK prepolymer:

The PTK prepolymer employed as a raw material for the block copolymer ofthis invention can be prepared in the following manner.

Namely, the PTK prepolymer can be prepared by having an alkali metalsulfide and a dihalogenated aromatic compound, which consistsprincipally of 4,4'-dichlorobenzophenone and/or4,4'-dibromobenzophenone, undergo a dehalogenation/sulfuration reactionin the presence of water in an organic amide solvent under the followingconditions (a)-(b):

(a) The ratio of the water content to the amount of the charged organicamide solvent is within a range of 2.5-15 (mol/kg).

(b) The reaction is conducted at a temperature within a range of60°-300° C. with the proviso that the reaction time at 210° C. andhigher is not longer than 10 hours.

The PTK prepolymer may contain some crosslinked structure and/orbranched structure introduced typically by allowing atrihalobenzophenone or higher polyhalobenzophenone to present in a smallamount in the polymerization reaction system.

<Production process of block copolymers (Process No. 1)>

As a production process for each block copolymer usable in thisinvention, may be described the process in which a PATE prepolymer isprepared in advance and at least one PTK block is formed in the presenceof the PATE prepolymer.

Practically, this process is the following two-step process:

A process for the production of a poly(arylene thioether) blockcopolymer comprising (X) at least one PTK block and (Y) at least onePATE block, which comprises at least the following two steps:

(i) heating in the presence of water an organic amide solvent containinga dihalogenated aromatic compound, which consists principally of adihalobenzene, and an alkali metal sulfide, whereby a reaction mixturecontaining a PATE prepolymer having predominant recurring units of theformula ##STR13## and reactive terminal groups is formed, and

(ii) mixing the reaction mixture, which has been obtained in the step(i), with a dihalogenated aromatic compound consisting principally of atleast one dihalobenzophenone selected from 4,4'-dichlorobenzophenone and4,4'-dibromobenzophenone, an alkali metal sulfide, an organic amidesolvent and water and heating the resultant mixture to form a PTK blockhaving predominant recurring units of the formula ##STR14## wherein the--CO-- and --S-- are in the para position to each other,

said first and second steps (i) and (ii) being conducted under thefollowing conditions (a)-(f):

(a) in the first step (i), the ratio of the water content to the amountof the charged organic amide solvent being 0.2-5 (mol/kg), the ratio ofthe amount of the charged dihalogenated aromatic compound to the amountof the charged alkali metal sulfide being 0.8-1.05 (mol/mol), and thepolymerization being conducted until the average polymerization degreeof the poly(arylene thioether) prepolymer becomes at least 10,

(b) in the second step, the ratio of the water content to the amount ofthe charged organic amide solvent being controlled within a range of2.5-15 (mol/kg),

(c) in the second step, the ratio of the total amount of the chargeddihalogenated aromatic compound, said total amount being the amount ofthe whole dihalogenated aromatic compounds including the dihalobenzeneand the dihalobenzophenone to the total amount of the charged alkalimetal sulfide, said latter total amount being the total amount of thealkali metal sulfide charged in the first step (i) and that charged inthe second step (ii), being controlled within a range of 0.95-1.2(mol/mol),

(d) the ratio of the charged amount of the dihalogenated aromaticcompound consisting principally of the dihalobenzophenone to the chargedamount of the dihalogenated aromatic compound consisting principally ofthe dihalobenzene being controlled within a range of 0.1-10 (mol/mol),

(e) the reaction of the second step ii) being conducted within atemperature range of 150°-300° C. with the proviso that the reactiontime at 210° C. and higher is not longer than 10 hours, and

(f) in the second step (ii), the reaction is conducted until the meltviscosity of the resulting block copolymer becomes 50-100,000 poises asmeasured at 350° C. and a shear rate of 1,200/sec.

<Production process of block copolymers (Process No. 2)>

As another production process for each block copolymer according to thisinvention, may be described the process in which PATE prepolymer and PTKprepolymers are prepared in advance and are then reacted to combine themtogether. This process is practically the following 3-step process:

A process for the production of a poly(arylene thioether) blockcopolymer comprising (X) at least one PTK block and (Y) at least onePATE block, which comprises at least the following three steps:

(i) heating in the presence of water an organic amide solvent containinga dihalogenated aromatic compound, which consists principally of adihalobenzene, and an alkali metal sulfide, whereby a first reactionmixture containing a PATE prepolymer having predominant recurring unitsof the formula

and reactive terminal groups is formed,

(ii) heating in the presence of water an organic amide solventcontaining a dihalogenated aromatic compound, which consists principallyof at least one dihalobenzophenone selected from4,4'-dichlorobenzophenone and 4,4'-dibromobenzophenone, an alkali metalsulfide, whereby a second reaction mixture containing a PTK prepolymerhaving predominant recurring units of the formula ##STR15## wherein the--CO-- and --S-- are in the para position to each other and reactiveterminal groups is formed, and

(iii) mixing and reacting the first reaction mixture, which has beenobtained in the first step (i) and contains the PATE prepolymer, withthe second reaction mixture obtained in the second step (ii) andcontaining the PTK prepolymer;

said first through third steps (i)-(iii) being conducted under thefollowing conditions (a)-(g):

(a) in the first step (i), the ratio of the water content to the amountof the charged organic amide solvent being 0.2-5 (mol/kg), the ratio ofthe amount of the charged dihalogenated aromatic compound to the amountof the charged alkali metal sulfide being 0.8-1.05 (mol/mol), and thepolymerization being conducted until the average polymerization degreeof the PATE prepolymer becomes at least 10,

(b) in the second step, the ratio of the water content to the amount ofthe charged organic amide solvent being controlled within a range of2.5-15 (mol/kg) and the reaction being conducted within a temperaturerange of 60°-300° C. with the proviso that the reaction time at 210° C.and higher is not longer than 10 hours,

(c) in the third step, the ratio of the water content to the amount ofthe charged organic amide solvent being controlled within a range of2.5-15 (mol/kg),

(d) in the third step, the ratio of the total amount of the chargeddihalogenated aromatic compound, said total amount being the amount ofthe whole dihalogenated aromatic compounds including the dihalobenzeneand the dihalobenzophenone to the total amount of the charged alkalimetal sulfide, said latter total amount being the total amount of thealkali metal sulfide charged in the first step (i) and that charged inthe second step (ii), being controlled within a range of 0.95-1.2(mol/mol),

(e) the ratio of the whole poly(arylene thioether) prepolymer to thewhole poly(arylene thioether-ketone) prepolymer being controlled at0.05-5 by weight,

(f) the reaction of the third step (iii) being conducted within atemperature range of 150°-300° C. with the proviso that the reactiontime at 210° C. and higher is not longer than 10 hours, and

(g) in the third step (iii), the reaction is conducted until the meltviscosity of the resulting block copolymer becomes 50-°100,000 poises asmeasured at 350° C. and a shear rate of 1,200/sec.

In the process for the production of each of the PTK prepolymer and theblock copolymer, it is preferable to use, as a reactor (includingequipment employed for provisional procedures of the polymerizationreaction, for example, those required for dehydration and the like), areactor made of a corrosion-resistant material at least at portions withwhich the reaction mixture is brought into direct contact. Thecorrosion-resistant material is supposed to be inert so that it does notreact with the reaction mixture. Preferred examples of thecorrosion-resistant material include titanium materials such as titaniumand titanium-containing alloys.

Further, in a final stage of the reaction, at least onehalogen-substituted aromatic compound having at least one substituentgroup having electron-withdrawing property at least equal to --CO--group (preferably, 4,4'dichlorobenzophenone and/or4,4'-dibormobenzophenone employed as a monomer) may be added to thereaction system to react it to the above-obtained block copolymer,whereby a block copolymer improved further in melt stability can beobtained. Here, it should be noted that the term "final stage of thereaction" as used herein means a period after the lapse of about onethird of the overall period of the reaction from the initiation thereof.Further, the amount of the halogen-substituted aromatic compound chargedin the final stage of the reaction is not included in theabove-described amount of the charged dihalogenated aromatic compound.

Thermoplastic Materials

The thermoplastic material usable in the present invention is obtainedby blending the poly(arylene thioether) block copolymer (Component A)optionally with at least one other thermoplastic resin (Component B)and/or at least one filler (Component C) in order to modify and/orimprove various physical properties of the block copolymer, such asmechanical properties, electrical properties, thermal properties andchemical properties, to modify and/or improve its processability and toreduce the production cost of the fibers. In addition, the compositionmay also be added with a basic compound (Component D) which is a meltstabilizer for Component A, optionally along with an antioxidant(Component E).

Other components of the thermoplastic material usable in the presentinvention will hereinafter be described specifically.

[Component B . . . Thermoplastic Resin]

Each thermoplastic material usable in the present invention may containas Component B at least one thermoplastic resin in a proportion of 0-50parts by weight, preferably 0-40 parts by weight, more preferably 0-30parts by weight, per 100 parts by weight of Component A. If theproportion of Component B exceeds 50 parts by weight, the mechanicalproperties, especially the durability at elevated temperatures will beimpaired.

As exemplary thermoplastic resins useful as Component B in the presentinvention, may be mentioned resins such as poly(arylene thioethers),poly(arylene thioether-ketones), aromatic polyether ketones, e.g., PEEKsand PEKs, polyamides (including Aramids), polyamideimides, polyesters(including aromatic polyesters and liquid crystalline polyesters),aromatic polysulfones, e.g., polysulfones and polyether sulfones,polyether imides, polyarylenes, poly(phenylene ethers), polycarbonates,polyester carbonates, polyacetals, fluoropolymers such aspolytetrafluoroethylene, polyolefins, polystyrenes, polymethylmethacrylates, and ABS; as well as elastomers such as fluororubbers,silicone rubbers, olefin rubbers, acrylic rubbers, polyisobutylenes(including butyl rubber), hydrogenated SBR, polyamide elastomers andpolyester elastomers. These thermoplastic resins may be used eithersingly or in combination.

Of the above thermoplastic resins, poly(arylene thioethers),particularly poly(arylene thioethers) containing predominant recurringunits of the formula ##STR16## (in a proportion of at least 50 wt. %),poly(arylene thioether-ketones) containing predominant recurring unitsof the formula ##STR17## wherein the --CO-- and --S-- are in the paraposition to each other, and mixtures thereof show excellentcompatibility when blended with the block copolymer of this invention,judging from the glass transition temperatures of the blends as measuredby a DSC, their crystallization temperatures Tc₁ from a glass state,their crystallization temperature Tc₂ from a molten state and the peakbehaviours of the melting points of their crystals. These compositionshave also been found to have the marked feature that they can providetransparent moldings under amorphous conditions when they are free ofany filler.

[Component C . . . Filler]

Each thermoplastic material usable in the present invention may containas Component C at least one filler in a proportion of up to 10 parts byweight per 100 parts by weight of Component A. If the proportion ofComponent C exceeds 10 parts by weight, there is a potential problemthat the processability may be reduced. Such a large proportion istherefore not preferred.

As exemplary fillers useful as Component C in the invention, may bementioned fibrous fillers such as glass fibers, carbon fibers, graphitefibers, silica fibers, alumina fibers, zirconia fibers, silicon carbidefibers and Aramid fibers as well as whiskers and the like includingpotassium titanate whiskers, calcium silicate (including wollastonite)whiskers, calcium sulfate whiskers, carbon whiskers, silicon nitridewhiskers and boron whiskers; and also inorganic fillers such as talc,mica, kaolin, clay, silica, alumina, silica-alumina, titanium oxide,iron oxides, chromium oxide, calcium carbonate, calcium silicate,calcium phosphate, calcium sulfate, magnesium carbonate, magnesiumphosphate, silicon, carbon (including carbon black), graphite, siliconnitride, molybdenum disulfide, glass, hydrotalcite, ferrite,samarium-cobalt, neodium-iron-boron, etc., all in a powder form.

These fillers may be used either singly or in combination.

[Component D . . . Basic Compound]

Addition of a specific basic compound to the thermoplastic material inthe present invention can reduce or prevent the melt viscosity increaseor crystallinity reduction due to thermal modification and/or thermaldeterioration, the sticking of thermal decomposition products at resinresidence areas of melt processing equipment, etc. upon melt processing.In addition, these stabilizing effects will be enhanced further bycombined use of the basic compound with a specific antioxidant.

As basic compounds, non-oxidative, heat-resistant and low volatilecompounds, more specifically, the hydroxides, oxides and aromaticcarboxylates of Group IIA metals of the periodic table other thanmagnesium, and aromatic carboxylates, carbonates, hydroxides, phosphates(including condensation products) and borates (including condensationproducts) of Group IA metals of the periodic table may be mentioned.

Among these basic compounds, the hydroxides and oxides of calcium andbarium, as well as the lithium, sodium and potassium salts of aromaticcarboxylic acids such as naphthalene monocarboxylic acid andpolycarboxylic acids, arylbenzoic acids, benzene monocarboxylic acid andpolycarboxylic acids and hydroxybenzoic acids are preferred. Among theabove-exemplified basic compounds, the hydroxides of calcium and bariumare particularly preferred.

The proportion of the basic compound in the thermoplastic material ofthis invention is 0.1-10 parts by weight, preferably 0.2-5 parts byweight, more preferably 0.3-2 parts by weight, all, per 100 parts byweight of the poly(arylene thioether) block copolymer. If the proportionof the basic compound is smaller than 0.1 part by weight, itsstabilizing effects cannot be exhibited to any sufficient degree. On theother hand, any proportions greater than 10 parts by weight involve apotential problem that the block copolymer may be decomposed orelectrical properties and the like may be deteriorated.

[Component E...Antioxidant]

As antioxidants used in combination with the basic compound, radicalchain terminators and peroxide decomposers, more specifically, hinderedphenolic compounds, phosphorus compounds and hindered amine compoundsmay be mentioned.

As exemplary hindered phenolic compounds, may typically be mentioned1,3,5-trimethyl-2,4,6-tris-(3,5-di-t-butyl-4-hydroxybenzyl)benzene andcompounds analogous thereto as well asoctadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]and2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate].

As phosphorus compounds, those containing a trivalent phosphorus atomare preferred.

As typical examples of such trivalent phosphorus compounds,tris(2,4-di-t-butylphenyl)phosphite,bis-(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite,distearylpentaerythritol diphosphite and tetrakis(2,4-di-t-butylphenyl)4,4'-biphenylenediphosphinate may be mentioned.

As typical exemplary hindered amine compounds,poly{[6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazin-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]-hexamethylene[(2,2,6,6-tetramethyl-4-piperydyl)iminol]} and compounds analogousthereto may be mentioned.

As antioxidants, low-volatile and decomposition-resistant ones,particularly, the above-described phosphorus compounds are preferred.These antioxidants may be used either singly or in combination. Whenused in combination, the combination of a radical chain terminator and aperoxide decomposer is preferred.

The proportion of the anti-oxidant in the composition of this inventionis 0-10 parts by weight, preferably 0.01-5 parts by weight, morepreferably 0.1-2 parts by weight, per 100 parts by weight of thepoly(arylene thioether) block copolymer. If the proportion of theanti-oxidant is smaller than 0.01 part by weight, it cannot exhibit asufficient stabilizing effect. On the contrary, any proportions greaterthan 10 parts by weight involve a potential problem that more gascomponents may be evolved and/or electrical properties and the like maybe deteriorated.

[Optional Components]

Each thermoplastic material usable in the present invention mayoptionally contain, as needed, additives such as light stabilizers, rustinhibitors, lubricants, surface-roughening agents, nucleating agents,mold releasing agents, colorants, coupling agents, flashing preventivesand/or antistatic agents.

Zinc compounds such as zinc oxide and zinc carbonate are particularlypreferred as scavengers for corrosive gas.

Blending Method

Thermoplastic materials usable in the present invention can each beprepared by one of various conventional blending methods including theblending of the individual components by a dry blending method.

Although all the components of the thermoplastic material includingoptional components may be added simultaneously, they can also beblended in an arbitrary order. For instance, after Component A andComponent D are mixed in advance, the mixture thus-obtained is addedwith the other components.

Component A and Component D are blended in advance by a dry-blendingmethod in which Component D in the form of a dry powder is added toComponent A, or by a wet method in which Component D in a wet form suchas a solution or a slurry is added to Component A and the solvent isthen removed to dry the resultant mixture. These mixtures can beseparately molten and kneaded further, as needed, to provide molten andkneaded mixtures. In this case, Component E may also be used jointly asdesired.

When Component D is blended after addition of Component B and/orComponent C to Component A, their blending may be carried out in thesame manner as the above-described blending method for Component D.

Dry blending method is preferred from the viewpoint that no drying stepbe required.

Production Method of Fibers

The fibers of this invention can be produced by charging a thermoplasticmaterial, which is the poly(arylene thioether) block copolymer or acomposition of the poly(arylene thioether) block copolymer, at least oneother thermoplastic resin and/or at least one filler, for example, intoa spinneret-equipped extruder in the air or preferably, in an inert gasatmosphere, extruding the thermoplastic material at an extrusiontemperature of 300°-400° C. through a spinneret, stretching theresultant fibers 1.2-8 times within a temperature range of 90°-190° C.and then heat-setting the thus-stretched fibers at 100°-340° C. for0.1-1,000 seconds. Upon extrusion through the spinneret, fibers aregenerally taken up at a draw down ratio (the ratio of the take-up speedof spun fibers to the discharge rate of the resin from the spinneret) offrom 1-50,000 times, preferably 5-5,000 times.

If the extrusion temperature from the spinneret is lower than the abovetemperature range, it is difficult to achieve smooth spinning. If it istoo high on the contrary, end breakages and deterioration of the resinare induced. Extrusion temperatures outside the above range are hencenot preferred. The fibers extruded from the spinneret are stretched inthe solid state and orientation is therefore imparted.

The stretching is carried out at a high temperature not higher than themelting point of the poly(arylene thioether) block copolymer, preferablyat 90°-190° C. The stretching step may be performed, for example, bystretching melt-spun and unstretched fibers in a dry heat bath or wetheat both of a high temperature or on a hot plate of a high temperature.If the stretching temperature is outside the specified temperaturerange, end breakages, fuzzing and/or melt bonding tends to take place.Stretching temperatures outside the above temperature range are hencenot preferred.

The draw ratio is 1.2-8 times. Draw ratios smaller than 1.2 times aredifficult to obtain high-strength fibers. On the other hand, draw ratiosgreater than 8 times encounter difficulties in stretching and induce endbreakages and/or fuzzing. Draw ratios outside the above range aretherefore not preferred. By applying heat setting subsequent tostretching, fibers having high strength and excellent dimensionalstability can be obtained.

Incidentally, the spinning extruder employed here may preferably be madeof a corrosion resistant metal at areas where the extruder is broughtinto contact with the molten resin. A vented spinning extruder isthought to be more preferred.

Block copolymers produced in the above manner feature high meltstability sufficient to permit application of conventionalmelt-processing techniques. Further, fibers produced from such blockcopolymers feature high heat resistance at elevated temperatures,namely, small reduction of strength even when used at elevatedtemperatures for a long period of time.

Physical Properties of Fibers

The poly(arylene thioether) block copolymer fibers according to thisinvention generally have a fiber diameter of 0.5-1,000 μm, preferably1-300 μm and have the following excellent physical properties:

(a) tensile strength being at least 10 kg/mm² when measured at 23° C.;

(b) tensile elongation being at least 5% when measured at 23° C.;

(c) heat shrinkage (200° C./30 min) being at most 20%.

(Measuring methods of physical properties)

Tensile strength:

JIS-L1013 was followed (sample length: 300 mm; drawing rate: 300mm/min).

Tensile elongation:

JIS-L1013 was followed.

Heat shrinkaqe (200° C./30 min):

After aging each fiber sample at 200° C. for 30 minutes, the degree ofshrinkage of the sample was determined.

Application Fields

The fibers according to this invention can be used, for example, asindustrial filters, heat-insulating materials, reinforcing fibers,insulating tapes, insulating cloths, fireproof wears, high-temperaturegloves, prepreg fibers, prepreg tapes, tension members for optical-fibercables, various textiles, etc.

ADVANTAGES OF THE INVENTION

According to this invention, fibers having excellent in strength, heatresistance and like are provided.

The fibers of this invention use, as a raw material, a high-crystallineblock copolymer, which has high melt stability enough for permittingapplication of conventional melt processing techniques, has a sufficientmolecular weight and can be produced at an economical cost, either aloneor as a thermoplastic material added with one or more components with aview toward modifying or otherwise changing the block copolymer.Therefore they have practical mechanical properties, especially,excellent durability at elevated temperatures.

EMBODIMENTS OF THE INVENTION

The present invention will hereinafter be described in further detail bythe following examples, experiments and comparative examples. It shouldhowever be borne in mind that the present invention is not limited onlyto the following examples and experiments so long as they do not departfrom the spirit or scope of the invention.

[Synthesis Experiment 1] (Synthesis of block copolymer by ProductionProcess No. 1)

(Synthesis of PATE prepolymer)

A titanium-lined reactor was charged with 225.5 kg of hydrated sodiumsulfide (water content: 53.9 wt. %) and 500 kg of N-methylpyrrolidone(hereinafter abbreviated as "NMP"). While gradually heating the contentsto 187° C. in a nitrogen gas atmosphere, 104 kg of an NMP solution,which contained 86.3 kg of water, and 34.9 moles of hydrogen sulfidewere distilled out. Thereafter, 171.8 kg of p-dichlorobenzene(hereinafter abbreviated as "PDCB") and 167 kg of NMP were then fed,followed by polymerization at 220° C. for 10 hours (PDCB/sodiumsulfide=0.9 mol/mol; water content/NMP=3 mol/kg).

After cooling to 50° C., a portion of the slurry of the reaction liquidcontaining the prepolymer was sampled out and the concentration ofactive terminal groups was measured by the method which will be set outsubsequently.

The concentration of terminal thiolate groups and terminal thiol groupswas 462×10⁻⁶ equivalent per gram of the prepolymer, while theconcentration of terminal chlorine groups was 34×10⁻⁶ equivalent pergram of the prepolymer. The number average molecular weight of theprepolymer as determined from the numbers of those terminal groups was4032 (average polymerization degree: 37).

Analytical methods:

<Analysis of terminal thiol groups or thiolate groups>

After completion of the polymerization of the prepolymer, a portion ofthe slurry as the reaction liquid was sampled out and then poured intowater to have the polymer precipitated. The prepolymer was collected byfiltration, washed in distilled water and then treated with dilutehydrochloric acid, whereby terminal thiolate groups were converted intothiol groups. The resulting polymer was washed for 30 minutes in purewater and for additional 30 minutes in acetone and then dried at roomtemperature under reduced pressure in a vacuum drier, thereby obtaininga polymer sample. Right after that, about 10 mg to 1 g of the polymersample was weighed and placed in a stopper-equipped test tube, followedby the addition of 2.5 ml of an acetone solution consisting of 2.5 ml ofacetone and 50 mmol of iodoacetamide. The test tube was hermeticallyclosed and then heated at 100° C. for 60 minutes. The test tube wasthereafter cooled with water and opened. The liquid-phase portion wasseparated. The absorbance at 450 nm (i.e., the absorbance of iodine) wasmeasured by means of a spectrophotometer.

Using a calibration curve prepared in advance with respect to the thiolcompound ##STR18## as a standard, the concentration of term groups wascalculated from the absorbance. (The amount of each sample should bechosen suitably so that the concentration of thiol groups in acorresponding acetone slurry falls within a range of 0.1-0.3 mmol.)Analysis was conducted three times on the same dried sample to determinethe average value of the concentration of terminal thiol groups.

<Analysis of terminal halogen groups>

Quantitative analysis of terminal halogen atoms was conducted using anX-ray fluorescence analyzer (model: "3080E2"; manufactured by RigakuDenki Kabushiki Kaisha).

<Determination of number average molecular weight>

Each number average molecular weight was determined from the data ofterminal thiol groups, including thiolate groups, and halogen groups inaccordance with the following equation: ##EQU1## (Synthesis of blockcopolymer)

A titanium-lined reactor containing 957.4 kg of the reaction liquidslurry of the PATE prepolymer was charged with 29.8 kg of hydratedsodium sulfide (water content: 54.0 wt. %), 80.5 kg of4,4'-dichlorobenzophenone (hereinafter abbreviated as "DCBP"), 328 kg ofNMP and 127.8 kg of water. After the reactor being purged with nitrogengas, the contents were heated to 260° C. at which they were polymerizedfor 2 hours.

The reaction conditions upon synthesis of the block copolymer were asfollows:

(1) The molar ratio of the total amount of the charged dihalogenatedaromatic compounds [the sum of the amount of PDCB charged upon synthesisof the prepolymer and the amount of DCBP charged upon synthesis of theblock copolymer] to the total amount of the charged alkali metal sulfide[the sum of the amount of effective sodium sulfide charged uponsynthesis of the prepolymer and the amount of sodium sulfide chargedupon synthesis of the block copolymer] was 1.01.

(2) The ratio of the amount of DCBP to the amount of PDCB, charged uponsynthesis of the prepolymer, was 32:68 by weight.

(3) The ratio of the water content to the organic amide (NMP) was about10 mol/kg.

(Collection of block copolymer)

The resultant reaction mixture in the form of a slurry was diluted witha substantially equal amount of NMP and the granular polymer thusobtained was collected by a screen having an opening size of 150 μm (100mesh). The polymer was washed three times with methanol and furtherthree times with water, and then dried at 100° C. for 24 hours underreduced pressure to obtain a block copolymer (Block Copolymer B₁). Thecollection rate of the Block Copolymer B₁ was 75%. (Inherent propertiesof Block Copolymer)

Block Copolymer B₁ was in the form of pearl-like granules having anaverage size of 680 μm and had a bulk density of 0.58 g/dl.

By an infrared (IR) spectrum analysis, a strong absorption peakattributed to ketone groups was observed at 1640 cm⁻¹. Wide angle X-raydiffraction which was conducted using"RAD-B System" (manufactured byRigaku Denki Kabushiki Kaisha) showed a diffraction patterncorresponding to the block copolymer, said pattern being apparentlydifferent from that of the corresponding PATE homopolymer or PTKhomopolymer or from that of a blend thereof.

The content of sulfur in Block Copolymer B₁ was determined by thecombustion flask method and ion chromatography (IC method). Namely,Block Copolymer B₁ was caused to burn in a flask and the resultingcombustion gas was absorbed in aqueous hydrogen peroxide solution,whereby the sulfur content of the block copolymer was converted intosulfate groups. The sulfur content was then quantitatively analyzedusing an ion chromatographic apparatus equipped with an electricalconductivity detector ("IC-500"; manufactured by Yokogawa ElectricCorporation).

The weight fraction W_(b) (wt. %) of the PATE recurring unit ##STR19##in the block copolymer can be calculated in accordance with thefollowing equation: ##EQU2##

By introducing a measured value W=24.3% and calculated values W₁ =15.01%and W₂ =29.63% into the above equation, W_(b) was determined to be63.5%.

(Physical properties of block copolymer)

Physical properties of the block copolymer are as follows:

Melt viscosity: 180 poises

Transition temperature:

Tg: 100° C.

Tm: 302° C. and 323° C.

Melt crystallization temperature:

Tmc (400° C.): 263° C.

Tmc (400° C./10 min): 230° C.

Melt crystallization enthalpy:

ΔHmc (400° C.): 53 J/g

Residual melt crystallization enthalpy:

ΔHmc (400° C./10 min): 42 J/g

Incidentally, Tg (glass transition temperature) and Tm (melting point)were measured at a heating rate of 10° C./min from room temperature by aDSC using a pressed sheet (pressed at 380° C.) and powdery polymer assamples, respectively.

[Synthesis Experiment 2]

(Synthesis of block copolymer by Production Process No. 2)

(Synthesis of PATE prepolymer)

A titanium-lined reactor was charged with 3.2 kg of hydrated sodiumsulfide (water content: 53.7 wt. %) and 6.0 kg of NMP. While graduallyheating the contents to 200° C. under a nitrogen gas atmosphere, 2.541kg of an NMP solution containing 1.326 kg of water and 0.38 mole ofhydrogen sulfide were distilled out. Then, 0.123 kg of water was added,followed by the feeding of a mixed solution of 2.35 kg of PDCB and 4.51kg of NMP. Polymerization was conducted at 220° C. for 10 hours(PDCB/sodium sulfide=0.86 mol/mol, water content/NMP= about 3 mol/kg),thereby obtaining a reaction slurry containing a PATE prepolymer. Thenumber average molecular weight of the prepolymer was 1530 (averagepolymerization degree: 14).

(Synthesis of PTK prepolymer)

A titanium-lined 20-l reactor was charged with 3.640 moles of DCBP,2.039 moles of hydrated sodium sulfide (water content: 53.7 wt. %), 176g of water and 4.004 kg of NMP. After the reactor being purged withnitrogen gas, the contents were maintained at 220° C. for 1 hour (watercontent/NMP= about 5 mol/kg) to obtain a reaction slurry containing aPTK prepolymer.

(Synthesis of block copolymer)

A charge pot equipped with a heater was mounted on the titanium-lined20-l reactor which had been charged with the reaction slurry containingthe PTK prepolymer (slurry temperature: 220° C.). The pot was chargedwith 9.12 kg of the reaction slurry containing the PATE prepolymer.After the reaction slurry being heated to 220° C., the reactor wascharged with the reaction slurry containing the PATE prepolymer and thenwith 1.146 kg of water. The contents were thereafter mixed.

The contents were maintained at 260° C. for 2 hours to react them. Afterthe contents being allowed to cool down to 240° C., a final stabilizingtreatment of the reaction was effected by adding 0.4356 mole of DCBP and0.5 kg of NMP and then reacting the contents at 240° C. for 0.2 hour.The reaction conditions upon synthesis of the block copolymer were asfollows:

(1) The molar ratio of the total amount of the charged dihalogenatedaromatic compounds [the sum of the amount of PDCB charged upon synthesisof the PATE prepolymer and the amount of DCBP charged upon synthesis ofthe PTK prepolymer] to the total amount of the charged alkali metalsulfide [the sum of the amount of sodium sulfide charged upon synthesisof the PATE prepolymer and the amount of sodium sulfide charged uponsynthesis of the PTK prepolymer] was 0.99.

(2) The ratio of PATE blocks to PTK blocks was approximately 60:40 (byweight).

(3) The ratio of the water content to the amount of the charged organicamide (NMP) was about 10 mol/kg. (Collection of block copolymer)

Collection was conducted in a similar manner to Synthesis Experiment 1,thereby obtaining a block copolymer (Block Copolymer B₂). The collectionrate was 78%.

(Physical properties of block copolymer)

Physical properties of Block Copolymer B₂ were as follows:

Melt viscosity: 650 poises.

Transition temperature:

Tg: 104° C.

Tm: 301° C. and 324° C.

Melt crystallization temperature:

Tmc (400° C.): 252° C.

Tmc (400° C./10 min): 221° C.

Melt crystallization enthalpy:

ΔHmc (400° C.): 43 J/g.

Residual melt crystallization enthalpy:

ΔHmc (400° C./10 min): 36 J/g.

Incidentally, the ratio (by weight) of the sum of PATE recurring unitsto the sum of PTK recurring units was 1.6 (62/38).

Synthesis Experiment 3]

(Synthesis of melt-stable PTK)

A titanium-lined reactor was charged with 90 moles of DCBP, 90 moles ofhydrated sodium sulfide (water content: 53.6 wt. %) and 90 kg of NMP(water content/NMP=5 mol/kg). After the reactor being purged withnitrogen gas, the contents were heated from room temperature to 240° C.over 1.5 hours and were then maintained at 240° C. for 2 hours to reactthem. Thereafter, to effect a stabilization treatment in a final stageof the reaction, 4.5 moles of DCBP, 18 kg of NMP and 90 moles of waterwere added, followed by a reaction at 240° C. for further 1 hour.

The reactor was cooled and the reaction mixture in the form of a slurrywas taken out of the reactor. The slurry was poured into about 200l ofacetone to have the resultant polymer precipitated. Thethus-precipitated polymer was collected by filtration and washed twicewith acetone and additionally twice with water. Acetone and water wereremoved to obtain the polymer in a wet form. The wet polymer thusobtained Was dried at 100° C. for 12 hours under reduced pressure toobtain Polymer PTK-1 as a fine powder having an average particle size of11.5 μm.

The melting point of Polymer PTK-1 (powder) was 360° C.

As an index of the molecular weight of PTK, the solution viscosity ofPTK-1 was measured.

Namely, the reduced viscosity η_(red) of PTK-1 as measured at 25° C. bya Ubbelohde's viscometer after dissolving the PTK-1 at a concentrationof 0.5 g/dl in 98% sulfuric acid was 0.63 dl/g.

As an index of the crystallinity of PTK, its density was measured.

Namely, the PTK powder was first of all placed between two sheets ofpolyimide film ("Kapton"; product of E. I. du Pont de Nemours & Co.,Inc.). It was preheated at 385° C. for 2 minutes and then press-formedat 385° C. for 0.5 minute by a hot press. It was then quenched to obtainan amorphous sample whose thickness was about 0.15 mm.

In addition, the amorphous sample thus-obtained was annealed at 280° C.for 30 minutes to prepare an annealed sample with an increased degree ofcrystallinity. The densities of the amorphous sample and annealed sample(crystallized sample) measured at 25° C. by means of a density gradienttube of the zinc chloride/water system were 1.30 g/cm³ and 1.35 g/cm³,respectively.

With respect to the PTK-1 powder obtained in Synthesis Experiment, theresidual melt crystallization enthalpy, ΔHmc (420° C./10 min) wasmeasured as an index of its melt stability. Namely, the temperaturecorresponding to a peak of melt crystallization measured by the DSC isrepresented by Tmc (420° C./10 min), while a residual meltcrystallization enthalpy, ΔHmc (420° C./10 min) was determined byconverting the area of the peak.

Described specifically, about 10 mg of PTK-1 (powder) were weighed.After holding the PTK-1 at 50° C. for 5 minutes in an inert gasatmosphere, it was heated up at a rate of 75° C./min to 420° C. and heldat that temperature for 10 minutes. While cooling the PTK-1 at a rate of10° C./min thereafter, its Tmc (420° C./10 min)and ΔHmc (420° C./10 min)were measured. As a result, ΔHmc (420° C./10 min) and Tmc (420° C./10min) were 43 J/g and 290° C., respectively.

In addition, ΔHmc (400° C./10 min) and Tmc (400° C./10 min) were 55 J/gand 313° C., respectively.

Example 1 (Spinning of multifilaments):

Under a nitrogen gas stream, Block Copolymer B₂ obtained in SynthesisExperiment 2 was charged into an extruder having a cylinder diameter of35 mm and equipped with a spinneret which had 40 fine holes, each of 0.4mm across. The block copolymer was melt-extruded at an extrusiontemperature of 340° C. and a draw down ratio, R₁ (the ratio of thetake-up speed of spun filaments to the discharge rate of the resin fromthe spinneret) of about 200. They were cooled through a nitrogen gasenvironment and then taken up at a take-up speed of 450 m/min, so thatunstretched fibers were obtained.

The unstretched fibers were stretched 3.5 times on a hot plate of 120°C. and then heat-set at 270° C. under a fixed length.

The thus-obtained fibers had the following physical properties. Fiberdiameter: 18 μm. Tensile strength (23° C.): 36 kg/mm² Tensile elongation(23° C.): 35%. Heat shrinkage (200° C./30 min): 16%. Density (25° C.):1.36 g/cm³.

Incidentally, the density was measured by the density gradient tubemethod of the lithium bromide/ water system.

EXAMPLE 2 & COMPARATIVE EXAMPLE 1: (DURABILITY TEST)

In order to evaluate the durability of each sample at elevatedtemperatures, the sample was placed in a temperature-controlled oven.Upon an elapse of a predetermined time period, its tensile strength wasmeasured.

Namely, employed as samples were the fibers obtained in Example 1(Example 2) and fibers produced in a similar manner to Example 1 exceptthat 40 wt. % of PTK-1 synthesized in Synthesis Experiment 3 and 60 wt.% of PATE [poly(p-phenylene thioether);"FORTRON W214"; product of KurehaChemical Industry Co., Ltd.] to give substantially the same compositionas Block Copolymer B₂ and the extrusion temperature was changed to 370°C. Portions of each sample were placed for 100, 200, 300, 400 and 500hours in ovens controlled at 1 90° C. and 215° C., respectively. Theywere thereafter taken out of the respective ovens, followed by themeasurement of tensile strength at room temperature.

The results are summarized as percent retentions in Table 1.

                                      TABLE 1                                     __________________________________________________________________________    Variations of tensile strength (percent retention) when held at               215° C. and 190° C. for long time                                           Holding time (Hours)                                              Surrounding 0       100      200     300      400     500                     temperature Percent retention (%)                                             (°C.)                                                                              Tensile strength                                                                      Tensile strength                                                                       Tensile strength                                                                      Tensile strength                                                                       Tensile strength                                                                      Tensile                 __________________________________________________________________________                                                          strength                Ex. 2                                                                             215     100     85       78      72       68      60                                  (36).sup.(1)                                                          190     100     95       91      88       85      82                                  (36).sup.(1)                                                      Comp.                                                                             215     100     78       63      50       40      30                      Ex. 1       (35).sup.(1)                                                          190     100     65       60      55       53      50                                  (35).sup.(1)                                                      __________________________________________________________________________     .sup.(1) Parenthesized value indicates the datum obtained when the percen     retention was 100%.                                                      

As is envisaged from Table 1, fibers available from a block copolymeruseful in the practice of this invention undergo much smaller variationsin strength compared with fibers available from a blend of PTK-1 andPATE.

This indicates that the block copolymer having a structure, in whichPATE blocks and PTK blocks are chemically coupled together, has afibrous structure thermally more stable than the mechanical blend ofhomopolymers of the respective components. Namely, the low melting-pointcomponent of the blend polymer is considered to be prone to structuralmodifications at elevated temperatures, resulting in significantvariations in strength.

EXAMPLE 3 (SPINNING OF MONOFILAMENTS):

Under a nitrogen gas stream, Block Copolymer B₂ obtained in SynthesisExperiment 2 was charged into an extruder having a cylinder diameter of35 mm and equipped with a spinneret which had 12 holes, each of 2.0 mmacross. The block copolymer was extruded at an extrusion temperature of340° C. and then cooled through hot water of 90° C., so that unstretchedfibers were obtained.

The unstretched fibers were stretched 4.1 times in hot glycerin of 115°C., 1.1 times in hot air of 180° C. and the subjected to relaxationtreatment at 0.98 times in hot air of 270° C.

The thus-obtained fibers had the following physical properties. Fiberdiameter: 210 μm. Tensile strength (23° C.): 23 kg/mm². Tensileelongation (23° C.): 31%. Heat shrinkage (200° C./30 min): 10.5%.Density (25° C.): 1.36 g/cm³.

The fibers were held for 320 hours in an environment of 210° C. andtheir tensile strength (23° C.) and tensile elongation (23° C.) weremeasured. They were 16.1 kg/mm² and 40.0%, respectively.

EXAMPLE 4:

To Block Copolymer B₁ obtained in Synthesis Experiment 1, stabilizerswere added in the prescribed amounts shown respectively in Table 2. Theresultant compositions were separately dry-blended in a tumbler blender,charged into a twin-screw extruder equipped with screws rotatable in thesame direction and having a cylinder diameter of 35 mm, molten andkneaded at a cylinder temperature of 350° C., extruded into strands,quenched and then chopped. Pellet samples of the respective compositionswere thus obtained.

Pellet samples were separately fed to an extruder equipped with aspinneret which defines 18 fine holes of 0.5 mm across, melt-extruded at70 times R₁ and an extrusion temperature of 370° C., and quenched atroom temperature in air, thereby obtaining corresponding unstretchedfilaments. Using a jig, they were stretched 4.5 times at 115° C. andthen heat-set at 280° C. for 2 minutes under tension. The physicalproperties of the resultant yarns and the melt stability of the pelletswere as shown in FIG. 2.

The long-run property of the composition added with Ca(OH)₂ as astabilizer and that of the composition added with both Ca(OH)₂ and theantioxidant were better compared with that of the block copolymer aloneand practically no thermally-decomposed products were observed stickingon the inner wall of the extruder.

<Measurement of Physical Properties>

Melt stability of pellets

Melt stability was evaluated based on η₃₀ ^(*) /η₅ ^(*) and η₆₀ ^(*) /η₅^(*) obtained in the following manner. About 20 g of each pellet samplewere placed in a barrel of a Capirograph, which barrel had been heatedat 350° C. The melt viscosity was measured 5 minutes, 30 minutes, 60minutes later, thereby determining η₅ ^(*), η₃₀ ^(*) and η₆₀ ^(*) (all,at a shear rate of 1200 sec⁻¹), respectively. The closer to 1 the ratio,the better the melt stability.

                                      TABLE 2                                     __________________________________________________________________________                           Example 4                                                                     4-1    4-2     4-3                                     __________________________________________________________________________    Block Copolymer B.sub.1 (parts by weight)                                                            100    100     100                                     Basic Compound Ca(OH).sub.2 (parts by weight)                                                        0      0.5     0.5                                     Antioxidant AO-220.sup.1) (parts by weight)                                                          0      0       0.2                                     Density (25° C.) (kg/cm.sup.3)                                                                1.36   1.36    1.36                                    Fiber diameter (μm) 30     30      30                                      Tensile strength (23° C.) (kg/mm.sup.2)                                                       24     24      24                                      Tensile modulus (23° C.) (kg/mm.sup.2)                                                        410    425     433                                     Tensile elogation (23° C.) (%)                                                                18     21      22                                      Durability (Percent retention) (210° C./350 hr)                        Tensile strength (%)   73     78      82                                      Tensile elongation (%) 125    118     111                                     Melt stability of pellets                                                     n.sub.30 */n.sub.5 *   1.2    0.9     0.96                                    n.sub.60 */n.sub.5 *   3.4    0.9     0.92                                    Remarks                No stabilizer                                                                        Stabilizer added                                                                      Stabilizer added                        __________________________________________________________________________     .sup.1 "AO220[; a compound analogous to 1, 3, 5trimethyl-2, 4, 6tris-(3,      5di-t-buty-4-hydroxybenzyl)benzene; product of Adeka Argus Chemical Co.,      .sup.2 Measuring method: JISL1013 was followed. Stress (modulus of            elasticity) at 10% deformation (elongation).                             

EXAMPLES 5-8 & COMPARATIVE EXAMPLES 2-4:

(Blend of block copolymer and PATE)

Block Copolymer B₂ and PATE [poly(p-phenylene thioether); melt viscosity(350° C., 1200 sec⁻¹): 630 poises; product of Kureha Chemical IndustryCo., Ltd.] were blended in the proportions shown in Table 3,respectively. Each of the resultant blends was formed into fibers in asimilar manner to Example 1 except that the extrusion temperature waschanged from 340° C. to 350° C., the take-up speed from 450 m/min to 250m/min, the stretching temperature from 120° C. to 110° C., the drawratio from 3.5 times to 3.3 times, and the heat-setting temperatureunder the fixed length from 270° C. to 250° C. The diameter of theresultant fibers was 25 μm. The physical properties are summarized inTable 3.

                                      TABLE 3                                     __________________________________________________________________________                                               High-temperature                                                              durability                                                     Tensile                                                                             Heat shrinkage                                                                         (percent retention of              Blending weight ratio of polymers                                                                 Tensile strength                                                                      elongation                                                                          factor   tensile strength)                  (by weight)         (23° C.)                                                                       (23° C.)                                                                     (200° C./30 min.)                                                               (230° C./30 min.)           Block copolymer B.sub.2                                                                     (RATE.sup.(1)                                                                       [kg/mm.sup.2 ]                                                                        [%]   [%]      [%]                                __________________________________________________________________________    Ex. 5                                                                             100        0    33      36    11       58                                 Ex. 6                                                                             90        10    33      35    13       58                                 Ex. 7                                                                             80        20    32      36    16       53                                 Ex. 8                                                                             70        30    31      36    18       52                                 Comp.                                                                             40        60    31      38    26       36                                 Ex. 2                                                                         Comp.                                                                             20        80    33      41    31       30                                 Ex. 3                                                                         Comp                                                                               0        100   35      43    39       26                                 Ex. 4                                                                         __________________________________________________________________________     .sup.(1) Poly (pphenylene thioether) (product of Kureha Chemical Industry     Co., Ltd.; Melt viscosity at 350° C. and 1200/sec.: 630 poises).  

As is shown in Table 3, no significant differences are observed in thetensile strength and elongation depending on the blending ratio of BlockCopolymer B₂ to PATE.

However, the heat shrinkage (200° C./30 min) which indicates thedimensional stability at elevated temperatures was found to undergo aconsiderable variation when the Block Copolymer B_(2/) PATE blendingratio changed from 70/30 to 40/60, because in the composition rangewhere Block Copolymer B₂ is contained less than PATE, the influence ofPATE having the lower melting point becomes dominant and the heatshrinkage hence increases.

Turning next to the durability at elevated temperatures (230° C./30 min)as an index of heat resistance, the reduction in durability increasedwhen the proportion of PATE became greater than that of the blockcopolymer.

It is thus understood from these results that the preferred blendingratio of Block Copolymer B₂ to the other thermoplastic resin, PATE is upto 70/30.

EXAMPLE 9:

(Blend of block copolymer and PTK)

Added to 100 parts by weight of Block Copolymer B₂ were 10 parts byweight of PTK-1 obtaine in Synthesis Experiment 3 and 0.5 part by weightof Ca(OH)₂ as a stabilizer. The resultant mixture was blended in atumbler blender, then molten, kneaded and extruded at a cylindertemperature of 370° C. by a twin-screw extruder having a cylinderdiameter of 35 mm and equipped with nozzles of 5 mm across and twoscrews rotatable in the same direction, thereby obtaining pellets.

Under a nitrogen gas stream, those pellets were charged into an extruderhaving a cylinder diameter of 35 mm and fitted with a spinneret defining40 fine holes of 0.5 mm across, melt-extruded at an extrusiontemperature of 370° C. and a draw down ratio, R₁ of about 200, andpassed and cooled through a nitrogen gas stream, thereby obtainingunstretched fibers.

The unstretched fibers were stretched 4.0 times on a hot plate of 140°C. and then passed through hot air of 275° C. for 2.5 seconds to conductheat-setting. The physical properties of the thus-obtained fibers are asfollows:

    ______________________________________                                        Fiber diameter:        22     μm                                           Tensile strength (23° C.)                                                                     33     kg/mm.sup.2                                     Tensile elongation (23° C.)                                                                   31%                                                    Heat shrinkage (200° C./3O min)                                                               18%                                                    Density                1.36   g/cm.sup.3.                                     ______________________________________                                    

We claim:
 1. A process for the production of poly(arylene thioether)block copolymer fibers from a thermoplastic material composed of:(A) 100parts by weight of a poly(arylene thioether) block copolymer (ComponentA) alternately comprising (X) at least one poly(arylenethioether-ketone) block having predominant recurring units of theformula ##STR20## wherein the --CO-- and --S-- are in the para positionto each other and (Y) at least one poly(arylene thioether) block havingpredominant recurring units of the formula ##STR21## (a) the ratio ofthe total amount of the poly(arylene thioether) block (Y) to the totalamount of said the poly(arylene thioether-ketone) block (X) ranging from0.05 to 5 by weight,(b) the average polymerization degree of thepoly(arylene thioether) block (Y) being at least 10, and (c) said blockcopolymer having a melt viscosity of 50-100,000 poises as measured at350° C. and a shear rate of 1,200/sec; (B) optionally, up to 50 parts byweight of at least one other thermoplastic resin (Component B); and (C)optionally, up to 10 parts by weight of at least one filler (CompenentC), which comprises melt-extruding the thermoplastic material at300°-400° C. through a spinneret, stretching the the resultant filamentsat 90°-190° C. and a draw ratio of 1.2-8 times, and then heat-settingthe thus-stretched filaments at 100°-340° C. for 0.1-1000 seconds. 2.The process as claimed in claim 9, wherein the poly(arylene thioether)block copolymer (Component A) has a melt crystalline temperature, Tmc(400° C./10 min) of at least 170° C. and a residual melt crystallizationenthalpy, ΔHmc (400° C./10 min) of at least 10 J/g, wherein Tmc (b 400°C./10 min) and ΔHmc (400° C./10 min) are determined by a differentialscanning calorimeter at a cooling rate of 10° C./min after the blockcopolymer is held at 50° C. for 5 minutes in an inert gas atmosphere,heated to 400° C. at a rate of 75° C./min and then held for 10 minutesat 400° C.
 3. The process as claimed in claim 1, wherein thepoly(arylene thioether) block (Y) in the poly(arylene thioether) blockcopolymer (Component A) has predominant recurring units of the formula##STR22##
 4. The process as claimed in claim 1, wherein thethermoplastic material further comprises, per 100 parts by weight of thepoly(arylene thioether) block copolymer (Component A), 0.1-10 parts byweight of at least one basic compound (Component D) selected from thegroup consisting of hydroxides, oxides and aromatic carboxylates ofgroup IIA metals of the periodic table other than magnesium, andaromatic carboxylates, carbonates, hydroxides, phosphates, includingcondensation products, and borates, including condensation products, ofgroup IA metals of the periodic table and 0-10 parts by weight of atleast one antioxidant (Component E) selected from the group consistingof hindered phenolic compounds, phosphorus compounds and hindered aminecompounds.
 5. The process as claimed in claim 1, wherein thethermoplastic resin (Component B) is at least one polymer selected frompoly(arylene thioethers) having predominant recurring units of theformula ##STR23## and poly(arylene thioether-ketones) having predominantrecurring units of the formula ##STR24## wherein the --CO-- and --S--are in the para position to each other.